#include <cstdio>

int n;
long long ans;

int main() {
#ifndef ONLINE_JUDGE
#ifdef LOCAL
  freopen("testdata.in", "r", stdin);
  freopen("testdata.out", "w", stdout);
#endif
#ifndef LOCAL
  freopen("fac.in", "r", stdin);
  freopen("fac.out", "w", stdout);
#endif
#endif

  scanf("%d", &n);
  for (int l = 1, r = 0; l <= n; l = r + 1) {
	  r = n / (n / l);
	  ans += (r - l + 1) * (n / l);
  }
  printf("%lld", ans);
  return 0;
}